Design 4 Drupal

Design4Drupal is just about the only design and frontend focused Drupal event in the US, and has a history of featuring some really fantastic speakers. Ethan Marcotte, Jeremy Keith, and even Dries Buytaert (the creator of Drupal) have presented keynotes over the past few years. I always enjoy presenting there, as it's always a great audience really focused on getting the very best design and user experience out of the Drupal platform.